Radiological Use of Fast Protons
TL;DR: The object of this paper is to acquaint medical and biological workers with some of the physical properties and possibilities of high-energy protons, and to be as simple as possible, let us consider only high- energy protons.
Abstract: Except for electrons, the particles which have been accelerated to high energies by machines such as cyclotrons or Van de Graaff generators have not been directly used therapeutically Rather, the neutrons, gamma rays, or artificial radioactivities produced in various reactions of the primary particles have been applied to medical problems This has, in large part, been due to the very short penetration in tissue of protons, deuterons, and alpha particles from present accelerators Higher-energy machines are now under construction, however, and the ions from them will in general be energetic enough to have a range in tissue comparable to body dimensions It must have occurred to many people that the particles themselves now become of considerable therapeutic interest The object of this paper is to acquaint medical and biological workers with some of the physical properties and possibilities of such rays To be as simple as possible, let us consider only high-energy protons: later we can generalize to oth
Citations
More filters
TL;DR: An overview of the state of the art of ion acceleration by laser pulses as well as an outlook on its future development and perspectives are given in this article. But the main features observed in the experiments, the observed scaling with laser and plasma parameters, and the main models used both to interpret experimental data and to suggest new research directions are described.
Abstract: Ion acceleration driven by superintense laser pulses is attracting an impressive and steadily increasing effort. Motivations can be found in the applicative potential and in the perspective to investigate novel regimes as available laser intensities will be increasing. Experiments have demonstrated, over a wide range of laser and target parameters, the generation of multi-MeV proton and ion beams with unique properties such as ultrashort duration, high brilliance, and low emittance. An overview is given of the state of the art of ion acceleration by laser pulses as well as an outlook on its future development and perspectives. The main features observed in the experiments, the observed scaling with laser and plasma parameters, and the main models used both to interpret experimental data and to suggest new research directions are described.
1,221 citations
TL;DR: A significant impact of Monte Carlo dose calculation can be expected in complex geometries where local range uncertainties due to multiple Coulomb scattering will reduce the accuracy of analytical algorithms and in these cases Monte Carlo techniques might reduce the range uncertainty by several mm.
Abstract: The main advantages of proton therapy are the reduced total energy deposited in the patient as compared to photon techniques and the finite range of the proton beam. The latter adds an additional degree of freedom to treatment planning. The range in tissue is associated with considerable uncertainties caused by imaging, patient setup, beam delivery and dose calculation. Reducing the uncertainties would allow a reduction of the treatment volume and thus allow a better utilization of the advantages of protons. This paper summarizes the role of Monte Carlo simulations when aiming at a reduction of range uncertainties in proton therapy. Differences in dose calculation when comparing Monte Carlo with analytical algorithms are analyzed as well as range uncertainties due to material constants and CT conversion. Range uncertainties due to biological effects and the role of Monte Carlo for in vivo range verification are discussed. Furthermore, the current range uncertainty recipes used at several proton therapy facilities are revisited. We conclude that a significant impact of Monte Carlo dose calculation can be expected in complex geometries where local range uncertainties due to multiple Coulomb scattering will reduce the accuracy of analytical algorithms. In these cases Monte Carlo techniques might reduce the range uncertainty by several mm.
1,027 citations
TL;DR: Results of clinical phase I-II trials provide evidence that carbon-ion radiotherapy might be beneficial in several tumor entities, and the progress in heavy-ion therapy is reviewed, including physical and technical developments, radiobiological studiesmore and models, as well as radiooncological studies.
Abstract: High-energy beams of charged nuclear particles (protons and heavier ions) offer significant advantages for the treatment of deep-seated local tumors in comparison to conventional megavolt photon therapy. Their physical depth-dose distribution in tissue is characterized by a small entrance dose and a distinct maximum (Bragg peak) near the end of range with a sharp fall-off at the distal edge. Taking full advantage of the well-defined range and the small lateral beam spread, modern scanning beam systems allow delivery of the dose with millimeter precision. In addition, projectiles heavier than protons such as carbon ions exhibit an enhanced biological effectiveness in the Bragg peak region caused by the dense ionization of individual particle tracks resulting in reduced cellular repair. This makes them particularly attractive for the treatment of radio-resistant tumors localized near organs at risk. While tumor therapy with protons is a well-established treatment modality with more than 60 000 patients treated worldwide, the application of heavy ions is so far restricted to a few facilities only. Nevertheless, results of clinical phase I-II trials provide evidence that carbon-ion radiotherapy might be beneficial in several tumor entities. This article reviews the progress in heavy-ion therapy, including physical and technical developments, radiobiological studiesmore » and models, as well as radiooncological studies. As a result of the promising clinical results obtained with carbon-ion beams in the past ten years at the Heavy Ion Medical Accelerator facility (Japan) and in a pilot project at GSI Darmstadt (Germany), the plans for new clinical centers for heavy-ion or combined proton and heavy-ion therapy have recently received a substantial boost.« less
619 citations
Additional excerpts
...Wilson, 1946"....
[...]
TL;DR: This review describes the physical, biologic, and technologic aspects of particle beam therapy and clinical trials investigating proton and carbon ion RT will be discussed in the context of their relevance to recent concepts of treatment with RT.
Abstract: Particle beams like protons and heavier ions offer improved dose distributions compared with photon (also called x-ray) beams and thus enable dose escalation within the tumor while sparing normal tissues. Although protons have a biologic effectiveness comparable to photons, ions, because they are heavier than protons, provide a higher biologic effectiveness. Recent technologic developments in the fields of accelerator engineering, treatment planning, beam delivery, and tumor visualization have stimulated the process of transferring particle radiation therapy (RT) from physics laboratories to the clinic. This review describes the physical, biologic, and technologic aspects of particle beam therapy. Clinical trials investigating proton and carbon ion RT will be summarized and discussed in the context of their relevance to recent concepts of treatment with RT.
578 citations
Cites background from "Radiological Use of Fast Protons"
...The use of protons and heavier ions was first proposed by Robert Wilson in 1946.(1) Since then, more...
[...]
TL;DR: The basic aspects of the physics of proton therapy are reviewed, including proton interaction mechanisms, proton transport calculations, the determination of dose from therapeutic and stray radiations, and shielding design.
Abstract: The physics of proton therapy has advanced considerably since it was proposed in 1946. Today analytical equations and numerical simulation methods are available to predict and characterize many aspects of proton therapy. This article reviews the basic aspects of the physics of proton therapy, including proton interaction mechanisms, proton transport calculations, the determination of dose from therapeutic and stray radiations, and shielding design. The article discusses underlying processes as well as selected practical experimental and theoretical methods. We conclude by briefly speculating on possible future areas of research of relevance to the physics of proton therapy.
455 citations
Cites background from "Radiological Use of Fast Protons"
...The history of proton therapy began in 1946 when Robert Wilson published a seminal paper in which he proposed to use accelerator-produced beams of protons to treat deep-seated tumors in humans (Wilson 1946)....
[...]
References
More filters
TL;DR: In particular, there is still wide divergence of opinion concerning the existence of any effect due to distribution of the ions in the irradiated tissue as mentioned in this paper, and this question is especially controversial among workers with x-rays and gamma rays, for the much discussed factor of wavelength must operate through differences in distribution of ions.
Abstract: It is an old and very generally accepted view ( e.g. , Aschkinass and Caspari, 1901; Redfield and Bright, 1924; Packard, 1931) that the biological effects of x-rays, cathode rays, and radiations from radio-active substances are associated in some way with the ionization they produce in the living material. However, there is as yet no general agreement concerning the exact nature of the part played by the ions.2 In particular, there is still wide divergence of opinion concerning the existence of any effect due to distribution of the ions in the irradiated tissue. This question is especially controversial among workers with x-rays and gamma rays, for the much discussed factor of wavelength, if existent, must operate through differences in distribution of ions.3
35 citations
TL;DR: In this paper, a collimated beam of fast neutrons, filtered for gamma-rays, resulting from neutron collisions in various hydrogenous and non-hydrogenous gases at pressures ranging from 3 mm to 3 atmospheres, was measured in ionization chambers of various types.
Abstract: The ionization produced by a collimated beam of fast neutrons, filtered for gamma-rays, resulting from neutron collisions in various hydrogenous and non-hydrogenous gases at pressures ranging from 3 mm to 3 atmospheres or resulting from collisions in various hydrogenous and non-hydrogenous wall materials has been measured in ionization chambers of various types. In large wire-defined gas-walled chambers the ionizing particles are the recoiling gas nuclei. The long range protons of hydrogenous gases expend part of their energy in the walls of the container at ordinary pressures; hence their ionization-pressure curves are quasiparabolic, becoming linear at higher pressures in accordance with theoretical predictions. The ionization-pressure curves for non-hydrogenous gases are linear except at low pressures. The limiting pressures at which linearity sets in lead to maximum values of the range and energy of the recoiling nuclei and indicate that in the beam of the 37-inch Berkeley cyclotron 5-Mev neutrons predominate. The slopes of the linear portions of the $i\ensuremath{-}p$ curves permit the calculation of the rate, ${E}_{j}$, at which energy is transferred from the neutron beam to nuclear constituents of the gas. The component of the ionization resulting from gamma-rays, produced in the target and in the walls of the collimator and chamber, was found less than 1 percent in hydrogenous gases and only 2-6 percent in other gases. From the rate of energy transfer and the neutron energy flux an approximate mean value of the $n\ensuremath{-}p$ cross section for neutron energy distribution of the beam was calculated; also the lower limits of similar cross sections for other nuclei have been estimated, these values containing both the scattering cross sections and those due to neutron absorption followed by disintegrations. In thimble chambers with 1-cm and in cylindrical chambers with 2-mm wall separations, the ionization results in large part from the recoiling wall nuclei. Ranges and energies of the heavier recoiling wall nuclei are indicated by the limiting pressures revealed in $i\ensuremath{-}p$ curves. The gamma-ray percentage is greater than in large volumed chambers. Neutron responses from most non-hydrogenous walls are practically independent of wall material. The excess response from hydrogenous walls is proportional to proton content. From the ${E}_{j}$ values measured in large chambers the energies absorbed per g of various biological substances and of hydrogenous and non-hydrogenous wall materials have been calculated, and (1) predict the respective responses measured in thimble chambers and (2) indicate that the energy absorption per g of tissue must be similar to that for a wall material like amber. Finally, analysis of the relative x-ray and neutron energy absorptions in such materials yields a factor ${k}_{n}g2$, which must be applied to reduce neutron exposures measured in certain hydrogenous-walled chambers to tissue doses.
34 citations
TL;DR: In this paper, the collision cross sections of a number of elements for high energy neutrons have been measured and the collision radius is given by the symmetrical meson theory of Rarita and Schwinger.
Abstract: Collision cross sections of a number of elements for high energy neutrons have been measured. Neutrons with a maximum energy of 25.4 Mev were obtained by bombarding lithium with 10.2 Mev deuterons. The reaction ${\mathrm{C}}^{12}(n,2n){\mathrm{C}}^{11}$, which has a measured threshold energy of approximately 21 Mev, was used as an energy sensitive detector for the transmission measurements. The cross section obtained for the neutron-proton collision process was 0.39 \ifmmode\pm\else\textpm\fi{}0.03\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}24}$ ${\mathrm{cm}}^{2}$. This is higher than the cross section calculated for $s$-scattering (0.35\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}24}$ ${\mathrm{cm}}^{2}$), but agrees well with the value of 0.40\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}24}$ ${\mathrm{cm}}^{2}$ predicted by the symmetrical meson theory of Rarita and Schwinger. Measurements on other nucleii ranging from carbon to mercury show that the collision radius is given by ${R}^{\ensuremath{'}}=b+{r}_{0}{A}^{\frac{1}{3}}$, with $b=1.7\ifmmode\pm\else\textpm\fi{}0.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}$ cm and ${r}_{0}=1.22\ifmmode\pm\else\textpm\fi{}0.15\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}$ cm. These measurements are in good agreement with the inelastic cross-section measurements of Grahame and Seaborg. The value of ${r}_{0}$ is somewhat lower than the values deduced from $p\ensuremath{-}n$ reactions, Coulomb energies, and $\ensuremath{\alpha}$-particle decay.
33 citations
TL;DR: The most promising way to use the betatron in therapy would be to send the original electrons accelerated in the vacuum tube directly into the patient as mentioned in this paper, since it has the right energy and a reasonable size.
Abstract: With the 20-million-volt electron beam of good intensity now produced in the University of Illinois betatron, questions about the practical use of high-energy radiations can be examined. The most promising way to use the betatron in therapy would be to send the original electrons accelerated in the vacuum tube directly into the patient. At 20 million volts these electrons will penetrate as far as 10 cm. and no farther. Thus no damage is done to the back of the patient. Furthermore, the ionization should reach a maximum 7 or 8 cm. beyond the entrance surface for the electrons, and the damage could be well localized within the body. About a 25- or 30-million-volt betatron would be ideal for this work, since it has the right energy and a reasonable size. Although a sufficiently intense beam of electrons now comes out of the betatron, it is not yet in a good enough state of collimation or control for practical use. The x-rays produced by this electron stream when it strikes a target cause an ionization intens...
24 citations